Maven2 property that indicates the parent directory

Question

I have a multi-modules project, like this one:

main-project/
    module1/
    module2/
        sub-module1/
        sub-module2/
        sub-module3/
        ...
    module3/
    module4/
    ...

I need to define a set of properties (that are dependent of the environment on which I want to release my project) in Maven2. I will not use <properties> as there is lots of properties... Thus, I use the Properties Maven2 plugin.

The properties files are located in the main-project/ directory. How can I set the correct directory in the main pom.xml, in order to specify to any children where to find the properties file?

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>properties-maven-plugin</artifactId>
    <version>1.0-alpha-1</version>
    <executions>
        <execution>
            <phase>initialize</phase>
            <goals>
                <goal>read-project-properties</goal>
            </goals>
            <configuration>
                <files>
                    <file>???/env_${env}.properties</file>
                </files>
            </configuration>
        </execution>
    </executions>
</plugin>

If I set only <file>env_${env}.properties</file>, then when Maven2 compiles the first module, it will not find the main-project/env_dev.properties file. If I set <file>../env_${env}.properties</file>, then an error will be raised at the parent level, or at any sub-module level...

Answer 1

Did you try ../../env_${env}.properties ?

Normally we do the following when module2 is on the same level as the sub-modules

<modules>
    <module>../sub-module1</module>
    <module>../sub-module2</module>
    <module>../sub-module3</module>
</modules>

I would think the ../.. would let you jump up two levels. If not, you might want to contact the plug in authors and see if this is a known issue.

Answer 2

I've found a solution to solve my problem: I search the properties files using the Groovy Maven plugin.

As my properties file is necessarily in current directory, in ../ or in ../.., I wrote a small Groovy code that checks these three folders.

Here is the extract of my pom.xml:

<!-- Use Groovy to search the location of the properties file. -->
<plugin>
    <groupId>org.codehaus.groovy.maven</groupId>
    <artifactId>gmaven-plugin</artifactId>
    <version>1.0-rc-5</version>
    <executions>
        <execution>
            <phase>validate</phase>
            <goals>
                <goal>execute</goal>
            </goals>
            <configuration>
                <source>
                    import java.io.File;
                    String p = project.properties['env-properties-file'];
                    File f = new File(p); 
                    if (!f.exists()) {
                        f = new File("../" + p);
                        if (!f.exists()) {
                            f = new File("../../" + p);
                        }
                    }
                    project.properties['env-properties-file-by-groovy'] = f.getAbsolutePath();
            </source>
            </configuration>
        </execution>
    </executions>
</plugin>
<!-- Now, I can load the properties file using the new 'env-properties-file-by-groovy' property. -->
<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>properties-maven-plugin</artifactId>
    <version>1.0-alpha-1</version>
    <executions>
        <execution>
            <phase>initialize</phase>
            <goals>
                <goal>read-project-properties</goal>
            </goals>
            <configuration>
                <files>
                    <file>${env-properties-file-by-groovy}</file>
                </files>
            </configuration>
        </execution>
    </executions>
</plugin>

This is working, but I don't really like it.

So, if you have a better solution, do not hesitate to post!

Answer 3

Try setting a property in each pom to find the main project directory.

In the parent:

<properties>
    <main.basedir>${project.basedir}</main.basedir>
</properties>

In the children:

<properties>
    <main.basedir>${project.parent.basedir}</main.basedir>
</properties>

In the grandchildren:

<properties>
    <main.basedir>${project.parent.parent.basedir}</main.basedir>
</properties>

Answer 4

In an answer to another question I showed how the maven-properties-plugin could be extended to use external property descriptors defined in Maven dependencies.

You could extend that idea to have multiple descriptor jars, each with the environment name as part of the artifactId, containing a ${env}.properties. Then you can use the property to select the appropriate jar and properties file, for example:

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>properties-ext-maven-plugin</artifactId>
  <version>0.0.1</version>
  <executions>
    <execution>
      <id>read-properties</id>
      <phase>initialize</phase>
      <goals>
        <goal>read-project-properties</goal>
      </goals>
    </execution>
  </executions>                              
  <configuration>
    <filePaths>
      <!--assume the descriptor project has a file in the root of the jar -->
      <filePath>${env}.properties</filePath>
    </filePaths>
  </configuration> 
  <dependencies>
    <!-- reference the properties jar for the particular environment-->
    <dependency>
      <groupId>some.descriptor.group</groupId>
      <artifactId>env-${env}-descriptor</artifactId>
      <version>0.0.1</version>
    </dependency>
  </dependencies>
</plugin>

Answer 5

<plugins>
  <plugin>
    <groupId>org.codehaus.groovy.maven</groupId>
    <artifactId>gmaven-plugin</artifactId>
    <version>1.0</version>
    <executions>
      <execution>
        <phase>validate</phase>
        <goals>
          <goal>execute</goal>
        </goals>
        <configuration>
          <source>
            import java.io.File
            project.properties.parentdir = "${pom.basedir}"
            while (new File(new File(project.properties.parentdir).parent, 'pom.xml').exists()) {
                project.properties.parentdir = new File(project.properties.parentdir).parent
            }
          </source>
        </configuration>
      </execution>
    </executions>
  </plugin>
  <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>properties-maven-plugin</artifactId>
    <version>1.0-alpha-2</version>
    <executions>
      <execution>
        <phase>initialize</phase>
        <goals>
          <goal>read-project-properties</goal>
        </goals>
        <configuration>
          <files>
            <file>${parentdir}/build.properties</file>
          </files>
        </configuration>
      </execution>
    </executions>
  </plugin>
  ...

Answer 6

I think that if you use the extension pattern used in the example for findbugs plugin & multimodule you may be able to set global properties related to absolute paths. It uses a top

example for multi module

The top level pom has an unrelated build-config project and a app-parent for the modules of the multimodule project. The app-parent uses extension to link itself to the build-config project and obtain resources from it. This is used to carry common config files to the modules. It may be a conduit for properties as well. You could write the top dir to a property file consumed by the build-config. (it seems too complex)

The problem is that a new top level must be added to the multi-module project to make this work. I tried to side step with a truly unrelated build-config project but it was kludgy and seemed brittle.